 |
| Titel |
Modeling the monthly mean soil-water balance with a statistical-dynamical ecohydrology model as coupled to a two-component canopy model |
| VerfasserIn |
J. P. Kochendorfer, J. A. Ramírez |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 10 ; Nr. 14, no. 10 (2010-10-27), S.2099-2120 |
| Datensatznummer |
250012457
|
| Publikation (Nr.) |
 copernicus.org/hess-14-2099-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| The statistical-dynamical annual water balance model of Eagleson (1978) is a
pioneering work in the analysis of climate, soil and vegetation interactions.
This paper describes several enhancements and modifications to the model that
improve its physical realism at the expense of its mathematical elegance and
analytical tractability. In particular, the analytical solutions for the root
zone fluxes are re-derived using separate potential rates of transpiration
and bare-soil evaporation. Those potential rates, along with the rate of
evaporation from canopy interception, are calculated using the two-component
Shuttleworth-Wallace (1985) canopy model. In addition, the soil column is
divided into two layers, with the upper layer representing the dynamic root
zone. The resulting ability to account for changes in root-zone water storage
allows for implementation at the monthly timescale. This new version of the
Eagleson model is coined the Statistical-Dynamical Ecohydrology Model (SDEM).
The ability of the SDEM to capture the seasonal dynamics of the local-scale
soil-water balance is demonstrated for two grassland sites in the US Great
Plains. Sensitivity of the results to variations in peak green leaf area
index (LAI) suggests that the mean peak green LAI is determined by some
minimum in root zone soil moisture during the growing season. That minimum
appears to be close to the soil matric potential at which the dominant grass
species begins to experience water stress and well above the wilting point,
thereby suggesting an ecological optimality hypothesis in which the need to
avoid water-stress-induced leaf abscission is balanced by the maximization of
carbon assimilation (and associated transpiration). Finally, analysis of the
sensitivity of model-determined peak green LAI to soil texture shows that the
coupled model is able to reproduce the so-called "inverse texture effect",
which consists of the observation that natural vegetation in dry climates
tends to be most productive in sandier soils despite their lower water
holding capacity. Although the determination of LAI based on complete or
near-complete utilization of soil moisture is not a new approach in
ecohydrology, this paper demonstrates its use for the first time with a new
monthly statistical-dynamical model of the water balance. Accordingly, the
SDEM provides a new framework for studying the controls of soil texture and
climate on vegetation density and evapotranspiration. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|